Preheat oven to 350 degrees. Roughly chop the soft pretzels into bite sized pieces, place into a large bowl. Pour turkey broth over pretzel pieces to soak. Melt butter in a large skillet over medium high heat. Add onions, celery and sausage slices sauté until vegetables translucent, stirring frequently. Toss cooked celery, onions, sausage, sage, rosemary and thyme with the soaking pretzel pieces until blended. Scrape mixture into a casserole dish or pan and press down lightly for even distribution. Cover pan with aluminum foil and bake for 15 minutes. Remove foil and continue to bake for another 15 minutes or until stuffing is fluffy and golden brown. Serve warm.